Support for multi-homing protocols

ABSTRACT

The present invention solves these problems with a new proxy binding update request and proxy binding acknowledgment messages having new indicators and identification information. Namely, the home agent/local mobility anchor will exchange proxy binding update messages and proxy binding acknowledge messages that include information such as mobile node identification (MN-ID), home network prefix (HNP), but can also include selective information fields such as, access type, handover indicator (HO), and interface identification (interface ID) By including new access type, indicator, and identification information, the local mobility anchor can respond to a binding update request message with a better understanding of the new connectivity request from the mobile node.

RELATED APPLICATION DATA

This application is related to Provisional Patent Application Ser. Nos.60/978,821 filed on Oct. 10, 2007 and 60/979,414 filed on Oct. 12, 2007,and priority is claimed for this earlier filing under 35 U.S.C. §119(e).The Provisional Patent Application is also incorporated by referenceinto this utility patent application.

TECHNICAL FIELD OF THE INVENTION

A method for allocating addressing for a mobile node on a communicationsystem using a handover indicator, access type indicator, and otheridentification fields.

BACKGROUND OF THE INVENTION

IP-based mobile systems provide for communication between at least onemobile node and a wireless communication network. The term “mobile node”includes a mobile communication unit (e.g., mobile terminal, “smartphones”, nomadic devices such as laptop PCs with wireless connectivity,as described in greater detail below). Among other elements, thewireless communication system includes a home network and a foreignnetwork. The mobile node may change its point of attachment to theInternet through these networks, but the mobile node will always beassociated with a single home network for IP addressing purposes. Thehome network includes a home agent and the foreign network includes aforeign agent—both of which control the routing of information packetsinto and out of their network.

The mobile node, home agent and foreign agent may be called differentnames depending on the nomenclature used on any particular networkconfiguration or communication system. For instance, a “mobile node”encompasses PC's having cabled (e.g., telephone line (“twisted pair”),Ethernet cable, optical cable, and so on) connectivity to the wirelessnetwork, as well as wireless connectivity directly to the cellularnetwork, as can be experienced by various makes and models of mobileterminals (“cell phones”) having various features and functionality,such as Internet access, e-mail, messaging services, and the like.Mobile nodes are sometimes called a user equipment, mobile unit, mobileterminal, mobile device, or similar names depending on the nomenclatureadopted by particular system providers. Generally, there is also acorrespondence node, which may be mobile or fixed, that may be locatedon the network for communicating with the mobile node.

A home agent may also be referred to as a Local Mobility Anchor, HomeMobility Manager, Home Location Register, and a foreign agent may bereferred to as a Mobile Access Gateway, Serving Mobility Manager,Visited Location Register, and Visiting Serving Entity. The terms mobilenode, home agent and foreign agent are not meant to be restrictivelydefined, but could include other mobile communication units orsupervisory routing devices located on the home or foreign networks.Foreign networks can also be called serving networks.

Registering the Mobile Node

Foreign agents and home agents periodically broadcast an agentadvertisement to all nodes on the local network associated with thatagent. An agent advertisement is a message from the agent on a networkthat may be issued under the Mobile IP protocol (RFC 2002) or any othertype of communications protocol. This advertisement should includeinformation that is required to uniquely identify a mobility agent (e.g.a home agent, a foreign agent, etc.) to a mobile node. Mobile nodesexamine the agent advertisement and determine whether they are connectedto the home network or a foreign network.

The mobile node will always be associated with its home network andsub-network for IP addressing purposes and will have information routedto it by routers located on the home and foreign network. If the mobilenode is located on its home network, information packets will be routedto the mobile node according to the standard addressing and routingscheme. If the mobile node is visiting a foreign network, however, themobile node obtains appropriate information from the agentadvertisement, and transmits a registration request message (sometimescalled a binding update request) to its home agent through the foreignagent. The registration request message will include a care-of addressfor the mobile node. A registration reply message (also called a bindingupdate acknowledge message) may be sent to the mobile node by the homeagent to confirm that the registration process has been successfullycompleted.

The mobile node keeps the home agent informed as to its location onforeign networks by registering a “care-of address” with the home agent.The registered care-of address identifies the foreign network where themobile node is located, and the home agent uses this registered care-ofaddress to forward information packets to the foreign network forsubsequent transfer onto the mobile node. If the home agent receives aninformation packet addressed to the mobile node while the mobile node islocated on a foreign network, the home agent will transmit theinformation packet to the mobile node's current location on the foreignnetwork using the applicable care-of address. That is, this informationpacket containing the care-of address will then be forwarded and routedto the mobile node on the foreign network by a router on the foreignnetwork according to the care-of address.

When mobile nodes move from one foreign network to another foreignnetwork, problems are sometimes encountered with the registration of thecare of addressing with the home agent or local mobility anchor.Further, multiple interfaces may be supported on a single or multipleforeign networks, which can include the different communication accesstypes 802.11d, 802.11g, FIRM, WiFi, WiMax, CDMA, or LTE. Problems can beencountered when the mobile node becomes coupled to different accesstypes on a single or multiple networks. Thus, it is a primary objectiveof this invention to provide addressing support for a mobile node wherethere is a handover to a new foreign network, a handover to a secondaccess type on the same foreign network (multiple access types aresupported on the foreign network), and/or multiple interfaces aresupported for connecting a mobile node to a foreign network.

SUMMARY OF THE INVENTION

The present invention solves these problems with a new proxy bindingupdate request and proxy binding acknowledgement messages having newindicators and identification information. Namely, the home agent/localmobility anchor will exchange proxy binding update messages and proxybinding acknowledge messages that include information such as mobilenode identification (MN-ID), home network prefix (HNP), but can alsoinclude selective information fields such as, access type, handoverindicator (HO), and interface identification (interface ID). Byincluding new access type, indicator, and identification information,the local mobility anchor can respond to a binding update requestmessage with a better understanding of the new connectivity request fromthe mobile node. The proxy binding update request and acknowledgementmessages may require new fields or expanded fields for the transmissionof the additional information, and the local mobility anchor/home agentwill also need to expand its binding cache entry table to support thesenew information fields. The invention can be implemented using a newprotocol application or modified messages from prior registrationapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention will become more readilyunderstood from the following detailed description and appended claimswhen read in conjunction with the accompanying drawings in which likenumerals represent like elements and in which:

FIG. 1 is a mobile IP-based communication system as used in the presentinvention using proxy messages that specify access type fields;

FIG. 2 is a binding cache entry table that supports these entries forthe system shown in FIG. 1;

FIG. 3 is a mobile IP-based communication system as used in the presentinvention using proxy messages that specify access type and handoverindicator fields; and

FIG. 4 is a binding cache entry table that supports these entries forthe system shown in FIG. 3.

The objects and features of the invention will become more readilyunderstood from the following detailed description and appended claimswhen read in conjunction with the accompanying drawings in which likenumerals represent like element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, the overall architecture of the IP-based mobile system isshown with a mobile mode 125, a home network 110 and foreign networks130 and 150, respectively. As shown in FIG. 1, the home network 110 hasa home agent or local mobility anchor 113. The local mobility anchor 113is coupled to the mobility agent gateway 155 on foreign network 150 bycommunication link 112, and local mobility anchor 113 is coupled to themobility agent gateway 135 on foreign network 130 by communication link115.

The mobility agent gateway 135 is coupled to the mobile node 125 throughthe radio access system comprised of the base station transceiver 139coupled to the antenna/transmitter 137 through the wirelesscommunication link 127. The mobility agent gateway 155 is coupled themobile node 125 using a second communication access type, such as WiMaxor WiFi, which is supported by the interface 141 and wirelesscommunication link 157. FIG. 1 also shows a connection to mobile node125 from the foreign agent 135 through connection 176 and second accessinterface 177. This interface is connected to mobile node 125 throughwireless communication link 180. In this embodiment, the communicationaccess type supported by connection interface 177 is the same as thesecond communication access type supported by interface 141. Thisembodiment has a limitation that multiple interfaces may be supported onthe networks, but on any given foreign network (such as network 150 or130), only one interface will be supported for each communication accesstype.

Mobile node 125 is shown electronically coupled to the foreign networks150 and 130 via the wireless communication link 157 and 127,respectively. The mobile node 125, however, can communicate with anytransceiver or access network coupled to a foreign network. That is,communications links 127 and 157 are radio transmitted links, but theselinks can be composed of any connection between two or more nodes on anetwork or users on networks or administrative domains.

The terms Local Mobility Anchor, home agent, and foreign agent may be asdefined in the Mobile IP Protocol (RFC 2002), but these agents are notrestricted to a single protocol or system. In fact, the term home agent,as used in this application, can refer to a home mobility manager, homelocation register, home serving entity, or any other agent at a homenetwork 110 having the responsibility to manage mobility-relatedfunctionality for a mobile node 125. Likewise, the term mobility agentgateway, as used in this application, can refer to a foreign agent,serving mobility manager, visited location register, visiting servingentity, or any other agent on a foreign network having theresponsibility to manage mobility-related functionality for a mobilenode 125.

In the mobile IP communications system shown in FIG. 1, the mobile node125 is identified by a permanent IP address. While the mobile node 125is coupled to its home network 110, the mobile node 125 receivesinformation packets like any other fixed node on the home network 110.When mobile, the mobile node 125 can also locate itself on foreignnetwork, such as network 130 or 150. When located on foreign network 130or 150, the home network 110 sends data communications to the mobilenode 125 by “tunneling” the communications to the foreign network 130 or150.

The mobile node 125 keeps the local mobility anchor 113 informed of itscurrent location, or foreign network association, by registering acare-of address with the local mobility anchor 113. Essentially, thecare-of address represents the foreign network where the mobile node 125is currently located. If the local mobility anchor 113 receives aninformation packet addressed to the mobile node 125 while the mobilenode 125 is located on a foreign network 130, the local mobility anchor113 will “tunnel” the information packet to foreign network 130 forsubsequent transmission to mobile node 125.

The foreign agent 135 participates in informing the local mobilityanchor 113 of the mobile node 125 current care-of address. The foreignagent 135 also receives information packets for the mobile node 125after the information packets have been forwarded to the foreign agent135 by the local mobility anchor 113. Moreover, the foreign agent 135serves as a default router for out-going information packets generatedby the mobile node 125 while connected to the foreign network 130.

The mobile node 125 participates in informing the local mobility anchor125 of its current location and requests connections to the associatedforeign network. When the mobile node 125 transitions to connecting to adifferent access type on the foreign network or a wholly differentforeign network (handover), the mobile node 125 obtains appropriateinformation regarding the address of the foreign network and/or theforeign agent from an agent advertisement.

When first connected to the local mobility anchor 113, mobile node 125would have created an entry on the binding cache entry table in FIG. 2that specified the mobile node identification for the mobile node 125.The access type field of information is included in the proxy bindingupdate request and the binding cache entry table in FIG. 2, with themobile node identification field. FIG. 2 is a binding cache entry table160 that possesses at least column and row entries for the mobile nodeidentification 165 and the access type 167. Other fields are maintainedon the binding cache entry table, but these are the pertinent entriesfor the consideration of the present invention.

Because each access type on the networks shown on FIG. 1 are limited toa single interface from each foreign network, the local mobility anchorwill check subsequent proxy binding update requests received from themobile node 125 to determine if this proxy binding update request hasthe same access type indicator as previously maintained on the bindingcache entry table 160 for that mobile node 125. If the same access typeindicator is found in a proxy binding update request as previouslymaintained on the binding cache entry table 160 for that mobile node125, the local mobility anchor 113 will recognize the situation as ahandover of the mobile node 125 to a new foreign network, such as ahandover of mobile node 125 from foreign network 130 to foreign network150. The local mobility anchor 113 will create a new binding cache entryfor the mobile node, and the care-of addressing and home network prefixwill be changed to designate the new foreign network as the networkwhere the mobile node 125 can be located, which information will betransmitted to the proper mobility access gateway 135 and the mobilenode 125.

If the comparison with the information in the proxy binding updaterequest shows a different access type connection for the mobile node125, the local mobility anchor will determine if the home network prefixshould designate the foreign network where the mobile node 125 waspreviously located without any indication of a handover to a new foreignnetwork. If that is the case, the entry for the mobile node 125 will bemodified on the binding cache entry table to indicate that the mobilenode 125 is still connected to the first foreign network 130, whichinformation will be transmitted to the proper mobility access gateway135 and the mobile node 125.

That is, this comparison may simple show the new connection for themobile node 125 is to a new access type, as opposed to a handover to anew foreign network. If so, the local mobility anchor 113 will respondto the proxy binding update request with a proxy binding update responsehaving a home network prefix indicator that points to the first foreignnetwork 130. In this manner, a receipt of new proxy binding updaterequest at the local mobility anchor 113 does not automatically create anew home network prefix for this mobile node, which solves some of theproblems with determining when a mobile node is simply connecting to anew access type on the same network or being handed over to a newforeign network.

In FIG. 3, the overall architecture of the IP-based mobile system isshown with a mobile mode 225, a home network 210 and foreign networks230 and 250, respectively. As shown in FIG. 3, the home network 210 hasa home agent or local mobility anchor 213. The local mobility anchor 213is coupled to the mobility agent gateway 255 on foreign network 250 bycommunication link 212, and local mobility anchor 213 is coupled to themobility agent gateway 235 on foreign network 230 by communication link215.

The mobility agent gateway 235 is coupled to the mobile node 225 throughthe radio access system comprised of the base station transceiver 239coupled to the antenna/transmitter 237 through the communication link227. The mobility agent gateway 255 is coupled to a second access type,such as WiMax or WiFi, through interface 241 coupled to the mobile node225 by communication link 257. FIG. 3 also shows a second connection ofthe same access type as supported by interface 241 for the connection ofthe mobile node 225 to foreign agent 255 through connection 276 andsecond access interface 277. This interface is connected to mobile node225 through communication link 280.

Mobile node 225 is shown electronically coupled to the foreign networks250 and 230 via the wireless communication link 257 (or 280) and 227,respectively. The mobile node 225, however, can communicate with anytransceiver or access network coupled to a foreign network. That is,communications links 227, 280 and 241 are radio transmitted links, butthese links can be composed of any connection between two or more nodeson a network or users on networks or administrative domains.

The terms Local Mobility Anchor, home agent, and foreign agent may be asdefined in the Mobile IP Protocol (RFC 2002), but these agents are notrestricted to a single protocol or system. In fact, the term home agent,as used in this application, can refer to a home mobility manager, homelocation register, home serving entity, or any other agent at a homenetwork 210 having the responsibility to manage mobility-relatedfunctionality for a mobile node 225. Likewise, the term mobility agentgateway, as used in this application, can refer to a foreign agent,serving mobility manager, visited location register, visiting servingentity, or any other agent on a foreign network having theresponsibility to manage mobility-related functionality for a mobilenode 225.

In the mobile IP communications system shown in FIG. 3, the mobile node225 is identified by a permanent IP address. While the mobile node 225is coupled to its home network 210, the mobile node 225 receivesinformation packets like any other fixed node on the home network 210.When mobile, the mobile node 225 can also locate itself on foreignnetwork, such as network 230 or 250. When located on foreign network 230or 250, the home network 210 sends data communications to the mobilenode 225 by “tunneling” the communications to the foreign network 230 or250.

The mobile node 225 keeps the local mobility anchor 213 informed of itscurrent location, or foreign network association, by registering acare-of address with the local mobility anchor 213. Essentially, thecare-of address represents the foreign network where the mobile node 225is currently located. If the local mobility anchor 213 receives aninformation packet addressed to the mobile node 225 while the mobilenode 225 is located on a foreign network 230, the local mobility anchor213 will “tunnel” the information packet to foreign network 230 forsubsequent transmission to mobile node 225.

The foreign agent 235 participates in informing the local mobilityanchor 213 of the mobile node 225 current care-of address. The foreignagent 235 also receives information packets for the mobile node 225after the information packets have been forwarded to the foreign agent235 by the local mobility anchor 213. Moreover, the foreign agent 235serves as a default router for out-going information packets generatedby the mobile node 225 while connected to the foreign network 230.

The mobile node 225 participates in informing the local mobility anchor225 of its current location and requests connections to the associatedforeign network. When the mobile node 225 transitions to connecting toforeign network 250, the mobile node 225 obtains appropriate informationregarding the address of the foreign network 250 and/or the foreignagent 255 from an agent advertisement.

When first connected to the local mobility anchor 213, mobile node 225would have created an entry on the binding cache entry table in FIG. 2that specified the mobile node identification for the first access type.The access type field of information is included in this binding cacheentry table in FIG. 2, with the mobile node identification field. FIG. 2is a binding cache entry table 260 that possesses at least column androw entries for the mobile node identification 265 and the access type267.

In the system shown on FIG. 3, multiple access types on a single foreignnetwork 250 are supported by multiple interfaces, such as interface 241and 277. Because the correspondence of the same access type on thebinding cache entry table of FIG. 2 may not indicate an inherenthandover to a different foreign network from the prior connected foreignnetwork, the proxy binding update request will include a handoverindicator for the analysis by the local mobility anchor 213.

The handover indicator would include a new field in the transmissionpacket that would indicate a handover to the same access type on thesame foreign network or a handover to a new foreign network. Thisinformation could also be indicated by a flag or other indicator to showthe type of handover that will be initiated, e.g. flag “1” equalshandover to same access type on same foreign network, flag “0” equalshandover to different foreign network. The new field could also indicateif the handover status is unknown, or this is an initial request for aproxy binding update request. Other fields can be maintained on thebinding cache entry table, and the transmission packets may be expandedto accommodate the new access type field of information.

The local mobility anchor 213 will check subsequent proxy binding updaterequests received from the mobile node 225 to determine the handoverindicator status. If the handover indicator indicates that the mobilenode is being connected to a different foreign network, the localmobility anchor 113 will initiate a protocol for a handover of themobile node 225 to a new foreign network, such as a handover of mobilenode 225 from foreign network 250 to foreign network 230. The localmobility anchor 213 will create a new binding cache entry for the mobilenode, and the care-of addressing and home network prefix will be changedto designate the new foreign network as the network where the mobilenode 225 can be located, which information will be transmitted to theproper mobility access gateway 235 and the mobile node 225.

If the handover indicator indicates that a handover is being requestedto different access type connection for the mobile node 225 on the sameforeign network 250, the local mobility anchor 213 will initiate aprotocol for designating a home network prefix for the foreign network250 where the mobile node 225 was previously located without anyindication of a handover to a new foreign network. If that is the case,the entry for the mobile node 225 will be modified on the binding cacheentry table to indicate that the mobile node 225 is still connected tothe first foreign network 250, which information will be transmitted tothe proper mobility access gateway 235 and the mobile node 225.

That is, this handover indicator may simply show the new connection forthe mobile node 225 is to a new interface for the same access type onthe same foreign network 250, as opposed to a handover to a new foreignnetwork. If so, the local mobility anchor 213 will respond to the proxybinding update request with a proxy binding update response having ahome network prefix indicator that points to the first foreign network250. In this manner, a receipt of new proxy binding update request atthe local mobility anchor 213 does not automatically create a new homenetwork prefix for this mobile node, which solves some of the problemswith determining whether a handover of the mobile node care-ofaddressing is necessary and whether it is necessary to designate a newforeign network or the same foreign network for this care-of addressingfor the mobile node.

As an alternative embodiment that is covered by the scope of theinvention, when first connected to the local mobility anchor 213, mobilenode 225 would have created an entry on the binding cache entry table inFIG. 4 that specified the mobile node identification for the firstaccess type and interface identification information. The access typefield of information is included in this binding cache entry table inFIG. 4, with the mobile node identification field, and the interfaceidentification information in column 269 would have indicated thespecific interface information for interface 241 or 277. FIG. 2 is abinding cache entry table 260 that possesses at least column and rowentries for the mobile node identification 265, the access type 267, andthe interface 269.

In the system shown on FIG. 3, multiple access types on a single foreignnetwork 250 are supported by multiple interfaces, such as interface 241and 277. Because the correspondence of the same access type on thebinding cache entry table of FIG. 4 would include additional informationthat the local mobility anchor would use to analyze whether the proxybinding update request relates to a handover to a different foreignnetwork 230 from the prior connected foreign network 250 or a handoverto a different interface for the same access type on the same foreignnetwork 250.

In addition to the access type information and the handover indicatordescribed above, the proxy binding update request would include a newfield in the transmission packet that would identify the interface thatwill be used to connect the mobile node to the foreign network. The newfield could also indicate if the interface identification is unknown.Other fields can be maintained on the binding cache entry table, and thetransmission packets may be expanded to accommodate the new access typefield of information.

The local mobility anchor 213 will check subsequent proxy binding updaterequests received from the mobile node 225 to determine the handoverindicator status. If the access type, handover indicator and interfaceidentification information indicates that the mobile node is beingconnected to a different foreign network, the local mobility anchor 113will initiate a protocol for a handover of the mobile node 225 to a newforeign network, such as a handover of mobile node 225 from foreignnetwork 250 to foreign network 230. The local mobility anchor 213 willcreate a new binding cache entry for the mobile node, and the care-ofaddressing and home network prefix will be changed to designate the newforeign network as the network where the mobile node 225 can be located,which information will be transmitted to the proper mobility accessgateway 235 and the mobile node 225.

If the access type, handover indicator, and interface identificationinformation indicates that a handover is being requested to differentaccess type connection for the mobile node 225 on the same foreignnetwork 250, the local mobility anchor 213 will initiate a protocol fordesignating a home network prefix for the foreign network 250 where themobile node 225 was previously located without any indication of ahandover to a new foreign network. If that is the case, the entry forthe mobile node 225 will be modified on the binding cache entry table toindicate that the mobile node 225 is still connected to the firstforeign network 250, which information will be transmitted to the propermobility access gateway 235 and the mobile node 225.

That is, the access type, handover indicator, and interface informationmay simply show the new connection for the mobile node 225 is to a newinterface for the same access type on the same foreign network 250, asopposed to a handover to a new foreign network. If so, the localmobility anchor 213 will respond to the proxy binding update requestwith a proxy binding update response having a home network prefixindicator that points to the first foreign network 250. In this manner,a receipt of new proxy binding update request at the local mobilityanchor 213 does not automatically create a new home network prefix forthis mobile node, which solves some of the problems with determiningwhether a handover of the mobile node care-of addressing is necessaryand whether it is necessary to designate a new foreign network or thesame foreign network for this care-of addressing for the mobile node.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.

Having described the invention, we claim:
 1. A method for registrationof a mobile node comprising: receiving a registration request message ata local mobility anchor relating to the mobile node connected to a firstforeign network, said registration request message including a mobilenode identifier, an access type identifier that indicates thatcommunication access type used to connect to the mobile node, a handoverindicator that specifies whether the registration request message isassociated with a handover to a new access type on the first foreignnetwork or a handover to a second foreign network, and an interfaceidentifier that indicates a specific access interface being used toconnect to the mobile node; correlating information received in theregistration request message against information on a cache entry tableassociated with the local mobility anchor; creating an entry on thecache entry table depending on whether a handover to the second foreignnetwork is detected or a handover to the new access type on the firstforeign network is detected; and transmitting a registration responsefrom the local mobility anchor with a network prefix depending onwhether said handover to the second foreign network is detected or saidhandover to a new access type on the first foreign network is detected.2. The method of registration in claim 1 wherein only one access typeper interface is supported on the foreign network and wherein the localmobility anchor detects the handover to the second foreign network inaccordance with registration request information including the accesstype indicator.
 3. The method of registration in claim 1 whereinmultiple interfaces support the same access type on the first foreignnetwork and the local mobility anchor detects the handover to the secondforeign network in accordance with registration request informationincluding the access type indicator.
 4. The method of registration inclaim 1 wherein multiple interfaces support the same access type on theforeign network and the local mobility anchor detects the handover to anew interface on the first foreign network in accordance withregistration request information including the interface identificationand handover indicator.
 5. The method of registration in claim 1 whereinthe cache entry table includes information relating to said mobile nodeconnected to the first foreign network, including the mobile nodeidentification information and the access type used to connect themobile node to the first foreign network.
 6. The method of registrationin claim 1 wherein the cache entry table includes information relatingto said mobile node connected to the first foreign network, includingthe mobile node identification information and the interfaceidentification for the interface used to connect the mobile node to thefirst foreign network.
 7. The method of registration in claim 1 whereinthe cache entry table includes information relating to said mobile nodeconnected to the first foreign network, including the mobile nodeidentification information, the access type, and the interfaceidentification for the interface used to connect the mobile node to thefirst foreign network.
 8. A method for registration of a mobile nodecomprising: receiving a registration request message at a local mobilityanchor relating to the mobile node on a first foreign network, saidregistration request message including a mobile node identifier, anaccess type identifier that indicates that communication access typeused to connect the mobile node, a handover indicator that specifieswhether the registration request message is associated with a handoverto a new access type on the first foreign network or a handover to asecond foreign network, and an interface identifier that indicates aspecific access interface being used to connect the mobile node;comparing information received in the registration request messageagainst information on a cache entry table associated with the localmobility anchor; and transmitting a registration response from the localmobility anchor with a network prefix depending on whether said handoverto the second foreign network is detected or said handover to a newaccess type on the first foreign network is detected.
 9. The method ofregistration in claim 8 wherein only one access type per interface issupported on the foreign network and the local mobility anchor detectsthe handover to the second foreign network based on the access typeindicator.
 10. The method of registration in claim 8 wherein multipleinterfaces support the same access type on the foreign network and thelocal mobility anchor detects the handover to the second foreign networkbased on the access type indicator and other information in theregistration request message.
 11. The method of registration in claim 8wherein multiple interfaces support the same access type on the foreignnetwork and the local mobility anchor detects the handover to a newinterface on the first foreign network based on the interfaceidentification and handover indicator in the request.
 12. The method ofregistration in claim 8 further comprising the step of: creating anentry on the cache entry table depending on whether a handover to thesecond foreign network is detected or a handover to a new accessinterface on the first foreign network is detected.
 13. The method ofregistration in claim 12 wherein the cache entry table includesinformation relating to said mobile node connected to the first foreignnetwork, including the mobile node identification information and theaccess type used to connect the mobile node to the first foreignnetwork.
 14. The method of registration in claim 12 wherein the cacheentry table includes information relating to said mobile node connectedto the first foreign network, including the mobile node identificationinformation and the interface identification for the interface used toconnect the mobile node to the first foreign network.
 15. The method ofregistration in claim 12 wherein the cache entry table includesinformation relating to said mobile node connected to the first foreignnetwork, including the mobile node identification information, theaccess type, and the interface identification for the interface used toconnect the mobile node to the first foreign network.
 16. The method ofregistration in claim 12 wherein the local mobility anchor detects thehandover to the first foreign network based on the access type indicatorbecause only one access type per interface is supported on the firstforeign network.
 17. A communications network comprising: a home networkhaving a local mobility agent coupled to one or more foreign networks,each foreign network having a mobile access gateway that is connected toone or more mobile node; the local mobility agent having a cache entrytable to maintain information relating to said one or more mobile nodesconnected to said foreign network; said local mobility agent configuredto provide information for mobile node connectivity in response to aregistration request message received by the local mobility agent basedon a comparison of information received in the request against theinformation on the cache entry table, said registration request messageincluding a mobile node identifier, an access type identifier thatindicates that communication access type used to connect the mobile nodeto at least one of the one or more foreign networks, a handoverindicator that specifies whether the registration request message isassociated with a handover to a new access type on a first foreignnetwork to which one of the one or more mobile nodes is connected or ahandover to a new foreign network, and an interface identifier thatindicates a specific access interface being used to connect the mobilenode to the one of the one or more foreign networks.
 18. Thecommunications network in claim 17 wherein only one access type perinterface is supported on the one or more foreign networks and the localmobility anchor detects a handover to the new foreign network based onthe access type indicator.
 19. The communications network in claim 17wherein multiple interfaces support the same access type on the one ormore foreign networks and the local mobility anchor detects a handoverto the new foreign network based on the access type indicator and otherinformation in the registration request message.
 20. The communicationsnetwork in claim 17 wherein multiple interfaces support the same accesstype on the one or more foreign networks and the local mobility anchordetects a handover to a new interface on the first foreign network basedon the interface identification and handover indicator in the request.